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NeHe Lesson01 crashes on UnregisterClass

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I'm new at this, I admit. I followed NeHe's lesson01 to the absolute letter. Other than a couple typos I corrected and fixed the linker errors and missing libs, I'm stuck on this. The program runs fine, but when I perform the fullscreen toggle or quit the program, it crashes (Could not unregister class), so something is going wrong in my killglwindow or is related. I probably don't quite understand it all yet either.
#include <windows.h>												// Header File For Windows
#include <gl\gl.h>													// Header File For The OpenGL32 Library
#include <gl\glu.h>													// Header File For The GLu32 Library
#include "glaux.h"													// Header File For The GLaux Library

HGLRC		hRC=NULL;												// Permanent Rendering Context
HDC			hDC=NULL;												// Private GDI Device Context
HWND		hWnd=NULL;												// Holds Our Window Handle
HINSTANCE	hInstance;												// Holds The Instance Of The Application

bool keys[256];														// Array Used For The Keyboard Routine
bool active=TRUE;													// Window Active Flag Set to TRUE By Default
bool fullscreen=TRUE;												// Fullscreen Flag Set To Fullscreen Mode By Default

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);				// Declaration For WndProc

GLvoid ReSizeGLScene(GLsizei width, GLsizei height)					// Resize And Initialize The GL Window
{
	if (height==0)													// Prevent A Divide By Zero By
	{
		height=1;													// Making Height Equal One
	}

	glViewport(0, 0, width, height);								// Reset The Current Viewport 

	glMatrixMode(GL_PROJECTION);									// Select The Projection Matrix
	glLoadIdentity();												// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f, (GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);										// Select The Modelview Matrix
	glLoadIdentity();												// Reset The Modelview Matrix
}

int InitGL(GLvoid)													// All Setup For OpenGL Goes Here
{
	glShadeModel(GL_SMOOTH);										// Enable Smooth Shading
	glClearColor(0.0f,0.0f,0.0f,0.0f);								// Black Background
	glClearDepth(1.0f);												// Depth Buffer Setup
	glEnable(GL_DEPTH_TEST);										// Enables Depth Testing
	glDepthFunc(GL_LEQUAL);											// The Type Of Depth Test To Do
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);				// Really Nice Perspective Calculations
	return TRUE;													// Initialization Went OK
}

int DrawGLScene(GLvoid)												// Here's Where We Do All The Drawing
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);				// Clear The Screen And The Depth Buffer
	glLoadIdentity();												// Reset The Current Modelview Matrix
	return TRUE;													// Everything Went OK
}

GLvoid KillGLWindow(GLvoid)											// Properly Kill The Window
{
	if (fullscreen)													// Are We In Fullscreen Mode?
	{
		ChangeDisplaySettings(NULL,0);								// If So Switch Back To The Desktop
		ShowCursor(TRUE);											// Show Mouse Pointer
	}
	if (hRC)														// Do We Have A Rendering Context?
	{
		if (!wglMakeCurrent(NULL,NULL))								// Are We Able To Release The DC And RC Contexts?
		{
			MessageBox(NULL,"Release of DC And RC Failed.","SHUTDOWN ERROR!",MB_OK | MB_ICONINFORMATION);
		}
		if (!wglDeleteContext(hRC))									// Are We Able To Delete The RC?
		{
			MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR!",MB_OK | MB_ICONINFORMATION);
		}
		hRC=NULL;													// Set RC To NULL
	}
	if (hDC && !ReleaseDC(hWnd,hDC))								// Are We Able To Release The DC
	{
		MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR!",MB_OK | MB_ICONINFORMATION);
		hDC=NULL;													// Set DC To NULL
	}
	if (!UnregisterClass("OpenGL",hInstance))						// Are We Able To Unregister Class
	{
		MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR!",MB_OK | MB_ICONINFORMATION);
		hInstance=NULL;												// Set hInstance to NULL
	}
}

BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
	GLuint		PixelFormat;										// Holds The Results After Searching For A Match
	WNDCLASS	wc;													// Window Class Structure
	DWORD		dwExStyle;											// Window Extended Style
	DWORD		dwStyle;											// Window Style
	RECT WindowRect;												// Grabs Rectangle Upper Left / Lower Right Values
	WindowRect.left=(long)0;										// Set Left Value To 0
	WindowRect.right=(long)width;									// Set Right Value To Requested Width
	WindowRect.top=(long)0;											// Set Top Value To 0
	WindowRect.bottom=(long)height;									// Set Bottom Value To Requested Height
	fullscreen=fullscreenflag;										// Set The Global Fullscreen Flag

	hInstance			= GetModuleHandle(NULL);					// Grab An Instance For Our Window
	wc.style			= CS_HREDRAW | CS_VREDRAW | CS_OWNDC;		// Redraw On Move, And Own DC For Window
	wc.lpfnWndProc		= (WNDPROC) WndProc;						// WndProc Handles Messages
	wc.cbClsExtra		= 0;										// No Extra Window Data
	wc.cbWndExtra		= 0;										// No Extra Window Data
	wc.hInstance		= hInstance;								// Set The Instance
	wc.hIcon			= LoadIcon(NULL, IDI_WINLOGO);				// Load The Default Icon
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW);				// Load The Arrow Pointer
	wc.hbrBackground	= NULL;										// No Background Required For GL
	wc.lpszMenuName		= NULL;										// We Don't Want A Menu
	wc.lpszClassName	= "OpenGL";									// Set The Class Name

	if (!RegisterClass(&wc))										// Attempt To Register The Window Class
	{
		MessageBox(NULL,"Failed To Register The Window Class.","ERROR!",MB_OK | MB_ICONEXCLAMATION);
		return FALSE;												// Exit And Return False
	}
	if (fullscreen)													// Attempt Fullscreen Mode?
	{
		DEVMODE dmScreenSettings;									// Device Mode
		memset(&dmScreenSettings,0,sizeof(dmScreenSettings));		// Makes Sure Memory's Cleared
		dmScreenSettings.dmSize=sizeof(dmScreenSettings);			// Size Of The Devmode Structure
		dmScreenSettings.dmPelsWidth	= width;					// Selected Screen Width
		dmScreenSettings.dmPelsHeight	= height;					// Selected Screen Height
		dmScreenSettings.dmBitsPerPel	= bits;						// Selected Bits Per Pixel
		dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;
		// Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar
		if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
		{
			// If The Mode Fails, Offer Two Options.  Quit Or Run In A Window.
			if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","Nehe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
			{
				fullscreen=FALSE;									// Select Windowed Mode (Fullscreen=FALSE)
			}
			else
			{
				// Pop Up A Message Box Letting User Know The Program Is Closing.
				MessageBox(NULL,"Program Will Now Close.","ERROR!",MB_OK|MB_ICONSTOP);
				return FALSE;										// Exit And Return FALSE
			}
		}
	}
	if (fullscreen)													// Are We Still In Fullscreen Mode?
	{
		dwExStyle=WS_EX_APPWINDOW;									// Window Extended Style
		dwStyle=WS_POPUP;											// Windows Style
		ShowCursor(FALSE);											// Hide Mouse Pointer
	}
	else
	{
		dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE;				// Window Extended Style
		dwStyle=WS_OVERLAPPEDWINDOW;								// Windows Style
	}
	AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle);		// Adjust Window To True Requested Size
	if (!(hWnd=CreateWindowEx(	dwExStyle,							// Extended Style For The Window
								"OpenGL",							// Class Name
								title,								// Window Title
								WS_CLIPSIBLINGS |					// Required Window Style
								WS_CLIPCHILDREN |					// Required Window Style
								dwStyle,							// Required Window Style
								0, 0,								// Window Position
								WindowRect.right-WindowRect.left,	// Calculate Adjusted Window Width
								WindowRect.bottom-WindowRect.top,	// Calculate Adjusted Window Height
								NULL,								// No Parent Window
								NULL,								// No Menu
								hInstance,							// Instance
								NULL)))								// Don't Pass Anything To WM_CREATE
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Window Creation Error.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	static PIXELFORMATDESCRIPTOR pfd=								// pfd Tells Windows How We Want Things To Be
	{
		sizeof(PIXELFORMATDESCRIPTOR),								// Size Of This Pixel Format Descriptor
		1,															// Version Number
		PFD_DRAW_TO_WINDOW |										// Format Must Support Window
		PFD_SUPPORT_OPENGL |										// Format Must Support OpenGL
		PFD_DOUBLEBUFFER,											// Must Support Double Buffering
		PFD_TYPE_RGBA,												// Request An RGBA Format
		bits,														// Select Our Color Depth
		0, 0, 0, 0, 0, 0,											// Color Bits Ignored
		0,															// No Alpha Buffer
		0,															// Shift Bit Ignored
		0,															// No Accumulation Buffer
		0, 0, 0, 0,													// Accumulation Bits Ignored
		16,															// 16Bit Z-Buffer (Depth Buffer)
		0,															// No Stencil Buffer
		0,															// No Auxiliary Buffer
		PFD_MAIN_PLANE,												// Main Drawing Layer
		0,															// Reserved
		0, 0, 0														// Layer Masks Ignored
	};
	if (!(hDC=GetDC(hWnd)))											// Did We Get A Device Context?
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Can't Create A GL Device Context.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))					// Did Windows Find A Matching Pixel Format?
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	if (!SetPixelFormat(hDC,PixelFormat,&pfd))						// Are We Able To Set The Pixel Format?
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Can't Set The PixelFormat.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	if (!(hRC=wglCreateContext(hDC)))								// Are We Able To Get A Rendering Context?
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	if (!wglMakeCurrent(hDC,hRC))									// Try To Activate The Rendering Context
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	ShowWindow(hWnd,SW_SHOW);										// Show The Window
	SetForegroundWindow(hWnd);										// Slightly Higher Priority
	SetFocus(hWnd);													// Sets Keyboard Focus To The Window
	ReSizeGLScene(width, height);									// Set Up Our Perspective GL Screen
	if (!InitGL())													// Initialize Our Newly Created GL Window
	{
		KillGLWindow();												// Reset The Display
		MessageBox(NULL,"Initialization Failed.","ERROR!",MB_OK|MB_ICONEXCLAMATION);
		return FALSE;												// Return FALSE
	}
	return TRUE;													// Success
}

LRESULT CALLBACK WndProc(	HWND	hWnd,							// Handle For This Window
							UINT	uMsg,							// Message For This Window
							WPARAM	wParam,							// Additional Message Information
							LPARAM	lParam)							// Additional Message Information
{
	switch (uMsg)													// Check For Windows Messages
	{
	case WM_ACTIVATE:												// Watch For Window Activate Message
		{
			if (!HIWORD(wParam))									// Check Minimization State
			{
				active=TRUE;										// Program Is Active
			}
			else
			{
				active=FALSE;										// Program Is No Longer Active
			}

			return 0;												// Return To The Message Loop
		}
	case WM_SYSCOMMAND:												// Intercept System Commands
		{
			switch (wParam)											// Check System Calls
			{
			case SC_SCREENSAVE:										// Screensaver Trying To Start?
			case SC_MONITORPOWER:									// Monitor Trying To Enter Powersave?
				return 0;											// Prevent From Happening
			}
			break;													// Exit
		}
	case WM_CLOSE:													// Did We Receive A Close Message?
		{
			PostQuitMessage(0);										// Send A Quit Message
			return 0;												// Jump Back
		}
	case WM_KEYDOWN:												// Is A Key Being Held Down?
		{
			keys[wParam] = TRUE;									// If So, Mark It As TRUE
			return 0;												// Jump Back
		}
	case WM_KEYUP:													// Has A Key Been Released?
		{
			keys[wParam] = FALSE;									// If So, Mark It As FALSE
			return 0;												// Jump Back
		}
	case WM_SIZE:													// Resize The OpenGL Window
		{
			ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));			// LoWord=Width, HiWord=Height
			return 0;												// Jump Back
		}
	}
	// Pass All Unhandled Messages To DefWindowProc
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(		HINSTANCE	hInstance,						// Instance
						HINSTANCE	hPrevInstance,					// Previous Instance
						LPSTR		lpCmdLine,						// Command Line Parameters
						int			nCmdShow)						// Window Show State
{
	MSG		msg;													// Windows Message Structure
	BOOL	done=FALSE;												// Bool Variable To Exit Loop
	// Ask The User Which Screen Mode They Prefer
	if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start Fullscreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
	{
		fullscreen=FALSE;											// Windowed Mode
	}
	// Create Our OpenGL Window
	if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
	{
		return 0;													// Quit If Window Was Not Created
	}
	while(!done)													// Loop That Runs Until done=TRUE
	{
		if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))					// Is There A Message Waiting?
		{
			if (msg.message==WM_QUIT)								// Have We Received A Quit Message?
			{
				done=TRUE;											// If So done=TRUE
			}
			else													// If Not, Deal With Window Messages
			{
				TranslateMessage(&msg);								// Translate The Message
				DispatchMessage(&msg);								// Dispatch The Message
			}
		}
		else														// If There Are No Messages
		{
			// Draw The Scene.  Watch For ESC Key And Quit Messages From DrawGLScene()
			if (active)												// Program Active?
			{
				if (keys[VK_ESCAPE])								// Was ESC Pressed?
				{
					done=TRUE;										// ESC Signalled A Quit
				}
				else												// Not Time To Quit, Update Screen
				{
					DrawGLScene();									// Draw The Scene
					SwapBuffers(hDC);								// Swap Buffers (Double Buffering)
				}
			}
			if (keys[VK_F1])										// Is F1 Being Pressed?
			{
				keys[VK_F1]=FALSE;									// If So Make Key FALSE
				KillGLWindow();										// Kill Our Current Window
				fullscreen=!fullscreen;								// Toggle Fullscreen / Window Mode
				// Recreate Our OpenGL Window
				if (!CreateGLWindow("NeHe's OpenGL Framework",640,480,16,fullscreen))
				{
					return 0;										// Quit If Window Was Not Created
				}
			}
		}
	}
	// Shutdown
	KillGLWindow();													// Kill The Window
	return (msg.wParam);											// Exit The Program
}


For the record, the comments are nice and straight in VC++2008. Doesn't translate well to copy-paste

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I'd have to recommend a modern book on OpenGL. Nehe tutorials are old and out of date with reality. You'll spend your time learning code that is bad, and possibly wrong. Your time and effort would be better spent with a more up-to-date lesson. While NeHe had great intentions in reality he himself was learning as he went and writing tutorials about it. Not likely the best plan honestly.

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